[pkg/ottl] update IsMatch to convert bool, double, and int to string.

[TylerHelmuth]

Component(s)

pkg/ottl

Is your feature request related to a problem? Please describe.

The IsMatch function, which is an important function for OTTL conditions, very strictly expects a string to be returned from its Getter otherwise the function returns nil. Since this function is commonly used with attributes, it often comes across non-string types.

Describe the solution you'd like

The function should be updated to convert "easy" types to string. I think we should start with bool, double, and int.

Describe alternatives you've considered

Add a String factory function that knows how to convert a type to a string. This is a useful function and I think should exist, but the ergonomics of including String with every attribute use with IsMatch seems bad. I think it is reasonable for the IsMatch function to handle this situation on its own.

Additional context

No response